The inositol phosphates in soils and manures: Abundance, cycling, and measurement

Abstract

This review focuses on recent advances in understanding the origins, abiotic and biotic cycling, and measurement of inositol phosphates (IP x) in manures and soils. With up to eight orthophosphates bound to inositol via ester linkages, this class of compounds has the potential to be unavailable to enzymatic hydrolysis when sorbed or in complex with soil metals, limiting the release of phosphorus (P) for uptake by plants. However, hydrolysis of IP x by microbial phytases in aquatic environments could result in a potent source of the eutrophication agent orthophosphate. This review discusses the forms and stereoisomers of IP x that have been identified in environmental samples. Next, it discusses the various techniques used to identify IP x , including extraction and concentration, separation techniques such as electrophoresis, spectroscopic methods such as phosphorus-31 nuclear magnetic resonance spectroscopy (31 P-NMR), mass spectrometry and X-ray absorption near-edge structure (XANES), and enzymatic techniques, such as enzyme hydrolysis (EH). Recent advances in knowledge about abiotic and biotic factors controlling the cycling of IP x in soil, manure and water are summarised, including soil characteristics affecting IP x sorption, transportation processes, and the microbial production and degradation of IP x. Finally, areas for future research focus are discussed.

Organic phosphorus in the aquatic environment

“…[71] Runoff from manure on pastures or from intensive agriculture has also been identified as a potential source of inositol phosphates to aquatic ecosystems. Non-ruminant vertebrates usually can't break down inositol phosphates, so the manure of animals such as pigs and chickens tends to contain significant quantities of these compounds, [80] especially if they are fed a diet rich in inositol phosphates (e.g. one containing a large amount of grain).…”

Microbial Phytases and Phytate: Exploring Opportunities for Sustainable Phosphorus Management in Agriculture

“…In addition to inorganic phosphates, a substantial fraction of total soil phosphorus is present in organic form [5] [6]. While the exact numbers may vary from one soil type to another, many authors estimate that various organic forms of phosphorus may constitute 30% -80% of the total soil P [7] [8].…”

“…Several excellent reviews on microbial phytases have recently been published and are highly recommended [5] [6] [19]- [25]. This review focuses on phytase science from the perspective of its substrate, phytate.…”

Speciation of Inositol Phosphates in Lake Sediments by Ion-Exchange Chromatography Coupled with Mass Spectrometry, Inductively Coupled Plasma Atomic Emission Spectroscopy, and 31P NMR Spectroscopy

“…3,4 However, the relatively poor detection limit (0.05 mg mL −1 ) generally limits the use of NMR to the mere identification of InsP n . Additionally, to improve recovery and resolution of the specific compounds studied, adequate analysis requires sample preconcentration, 5,6 introducing the risk of sample loss and sample degradation.…”

“…Previously described methods have produced a mixture of InsP n via autoclaving, heating in acid, or enzymatic treatment. 11,16,18,19 The methods involving increased temperatures produced a more evenly distributed range of InsP n with a better yield of InsP 4 and InsP 5 and was therefore adopted in this study, albeit with modifications and significantly scaled down.…”